Structural Breakstem Fasteners: Monobolt®, Hemlok®, Maxlok® and Avtainer®
In short: Structural breakstem fasteners are blind fasteners with a mechanically locked stem, giving much higher strength and vibration resistance than standard rivets. Monobolt®, Hemlok®, Maxlok® and Avtainer® each suit different materials and joints.
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Standard blind rivets handle most light assembly work. When a joint must carry higher loads and resist vibration, the answer is a structural breakstem fastener. Like a blind rivet, it is installed from one side. Unlike a standard rivet, its stem is mechanically locked into the body, so it adds strength, fills the hole and cannot rattle loose.
Monobolt®
A multi-grip structural fastener with a visible lock and a completely sealed joint. It is used in automotive, commercial vehicles, solar energy, construction and cabinet work.
- Excellent sheet take-up: it pulls together and closes large gaps
- A visible lock for quick, easy inspection
- One fastener covers a range of material thicknesses
- High shear and tensile strength
- The locked stem prevents rattling and electrical problems from loose stems
Hemlok®
A high-strength structural fastener with a large, neatly formed tail that spreads the clamp load on the rear sheet.
- Exceptional shear and tensile strength
- A large blind-side bearing area, ideal for thin sheet
- An interference lock from a splined stem
- Strong, vibration-resistant joints
Maxlok®
A versatile structural fastener with an extensive grip range, ideal where material thicknesses vary or production changes often.
- A wide grip range, which means fewer fasteners to stock
- High shear and tensile strength with high-speed assembly
- Excellent vibration resistance
- TIR approved and easy to inspect for tampering
Avtainer®
A high-strength steel fastener for joining composite materials to metal, such as GRP vehicle panels.
- Prevents cracking and pull-through of composites
- An under-head seal keeps the joint sealed
- An internally locked stem gives a secure, vibration-resistant joint
- A low-profile head for a neat finish
Choosing between them
Start with the materials and the load: Hemlok® for thin sheet, Avtainer® for composites, Maxlok® where thicknesses vary, and Monobolt® for sealed, inspectable general structural joints. For the heaviest joints, consider a lockbolt. All are installed with Avlock’s riveting tools, and the full range is on the Light Engineering page.